Capella: the little goat

In the next few months I plan to have an occasional series on the 20 brightest stars in the sky. Originally I was planning to start at 1 and work down, but I thought it made more sense to deal with them when they were most visible. So this month I’ll be writing about Capella, Sirius, Procyon, and Rigel.

Capella is the sixth brightest star in the sky, and third brightest in the northern hemisphere. It belongs to the constellation of Auriga, the Charioteer. As the title of this post indicates, the Charioteer is often shown cradling a goat in his arm, with the kids (or a whip). He also seems to have lost his chariot, which isn’t part of the constellation.

There are two Graeco-Roman myths about Auriga, neither of which mentions goats. It may be that the goat and kids were a later addition, as one story has it that Zeus wished to reward his goat nurse, Amalthea, and placed her in the stars as Capella. He also turned her horn into the Cornucopia, which could never be emptied of its rich food.

Capella has also been associated with the nymph who owned Amalthea. The goat’s Gorgon-like appearance led Zeus to skin it and wear the hide during the war with the Titans. This aegis helped turn the tide, and thus Amalthea and her kids were placed in the stars as Capella and the Haedi, or Kids. (Zeta, and Eta Aurigae) Before Ptolemy merged the two in his Almagest, the Goats were a constellation of their own. The Greeks considered that the heliacal rising (at sunrise) of the Goats was a cue for spring storms.

Auriga, with Capella clearly shown.
Auriga, with Capella clearly shown.

Part of the reason for Capella’s brightness is that it has hidden help; it’s actually a four-star system composed of two binary stars. The first, and larger pair, appear to be on their way to becoming red giants, while the other two are much fainter red dwarfs. The larger stars are currently still yellow, and will look that colour through a telescope.

Capella is the brightest star near the celestial pole (sorry, Polaris) and apparently it has put in time as the pole star, along with Aldebaran. For an explanation of why the pole star changes from time to time. see here.

Sidney_Hall_-_Urania's_Mirror_-_Auriga

Eta Aurigae, the fourth star in the Goats, is also a binary star, this time self-eclipsing. There is only one star visible, which disappears from view every 27 years. It always comes back, just the same as before, which has led to several theories about what is going on, but for now it’s one of the minor mysteries of the universe.

The Chinese saw more than one chariot in Auriga, calling it the Chariots of the Five Emperors. (The other four stars are Beta, Theta, Kappa and Gamma Aurigae: the shoulder, wrist, and foot of the Charioteer, and a star in the Kids.)

In ancient Hindu mythology, Capella was the head of Brahma, and (my favourite) in Inuit starlore Capella (Alpha Aurigae), Menkalinan (Beta Aurigae), Pollux (Beta Geminorum), and Castor (Alpha Geminorum) formed a constellation called Quturjuuk, “Collarbones”.

Finally, the Mescalero Apaches of New Mexico have a rather touching myth involving Capella and a few other stars in Auriga. It involves two sisters who shared a husband rather than be separated. When one of the sisters was dying, the Creator granted their wish to stay together, and put them in the sky as three stars, Capella, Eta and Iota Aurigae. Capella’s appearance was sign that the girls’ puberty rite should begin.

PS – In traditional astrology, stars other than those in the zodiac constellations were important. The fixed stars, as they were called, because they didn’t move around like the planets, were just as important to ancient and medieval astrology as the planets. Capella was one of these, and in a horoscope it was seen as combining the influences of Mars and Mercury. Its presence was seen as fortunate, and it betokened inquisitiveness, open-mindedness, and powerful friends.

If you like the image at the top, click here.

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